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by iammaxus
3896 days ago
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High-speed gearing is indeed very difficult, but jet engines already typically have two separate, concentric rotating units (spools: https://en.wikipedia.org/wiki/Turbofan#Basic_two_spool). Also, as the article mentions, turboprops (essentially jet engines connected to a propeller) already commonly use gearing. I guess you can think of it as a turboprop with a duct. The reality is probably just that this is a solvable problem that just wasn't worth the work while there were easier efficiency gains to be had. |
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Yes, everyone knows that, but the spools are not connected by a set of gears as they are in the P&W's new engine.
> Also, as the article mentions, turboprops (essentially jet engines connected to a propeller) already commonly use gearing. I guess you can think of it as a turboprop with a duct.
The new engine is ALSO unlike most installations of turboprop engines in that the fan is driven by the power spool, not a free turbine. The free turbine (in turboprops that have them), which powers the reduction gears for the propeller, runs at a much lower speed than the power turbine.